CS89712
3.18.18 Test Control Register (TestCTL, address offset 0118h)
7
6
5:0
F
E
D
DisableLT
011001
FDX
C
B
A
9
8
Disable Backoff
RSVD
ENDEC loop
TestCTL controls the diagnostic test modes of the CS89712.
Bit
Description
011001: These bits provide an internal address used by the CS89712 to identify this as register
19, the Test Control Register.
DisableLT: When set, the 10BASE-T interface allows packet transmission and reception
regardless of the link status. DisableLT is used in conjunction with the LinkOK (Register 14,
LineST, Bit 7) as follows:
LinkOK
0
0
1
DisableLT
0
1
N/A
No packet transmission for reception allowed.
Transmitter sends link impulses.
DisableLT overrides LinkOK to allow packet
transmission and reception. Transmitter does not
send link pulses.
Disable has no meaning if LinkOK = 1.
ENDECloop: When set, the CS89712 enters internal loopback mode where the internal
Manchester encoder output is connected to the decoder input. The 10BASE-T are disabled.
When clear, the CS89712 is configured for normal operation
Disable Backoff: When set, the backoff algorithm is disabled. The CS89712 transmitter looks
only for completion of the inter packet gap before starting transmission. When clear, the back-
off algorithm is used.
FDX: When set, 10BASE-T full duplex mode is enabled and CRS (Register 14, LineST, Bit E)
is ignored. This bit must be set when performing loopback tests on the 10BASE-T port. When
clear, the CS89712 is configured for standard half-duplex 10BASE-T operation.
RSVD: Reserved; must be a “0” when writing to this register.
Table 83. Test Control
At reset, if no EEPROM is found by the CS89712, then the register has the following initial state. If an EEPROM is
found, then the register’s initial value may be set by the EEPROM. See Section 2.24, “Programming the EEPROM”.
Reset value is: 0000 0000 0001 1001
3.19 Initiate Transmit Registers
3.19.1 Transmit Command Request Register (TxCMD, address offset 144h)
7:6
5:0
F
TxStart
001001
E
D
TxPadDis
C
B
InhibitCRC
A
9
8
Onecoll
Force
The word written to offset 0144h tells the CS89712 how the next packet should be transmitted. Note that this Ether-
net Port location is write-only, and the written word can be read from Ethernet address offset 0108h. The
DS502PP2
133